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First Application of the Local Ensemble Tangent Linear Model (LETLM) to a Realistic Model of the Global Atmosphere

Sergey Frolov, Douglas R Allen, Craig H Bishop, Rolf Langland, Karl W Hoppel, David D Kuhl

MONTHLY WEATHER REVIEW | AMER METEOROLOGICAL SOC | Published : 2018

Abstract

The local ensemble tangent linear model (LETLM) provides an alternative method for creating the tangent linear model (TLM) and adjoint of a nonlinear model that promises to be easier to maintain and more computationally scalable than earlier methods. In this paper, we compare the ability of the LETLM to predict the difference between two nonlinear trajectories of the Navy's global weather prediction model at low resolution (2.5° at the equator) with that of the TLM currently used in the Navy's four-dimensional variational (4DVar) data assimilation scheme. When compared to the pair of nonlinear trajectories, the traditional TLM and the LETLM have improved skill relative to persistence everywh..

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University of Melbourne Researchers